1. Field of the Invention
The present invention relates to an electron projection lithography apparatus using secondary electrons. More particularly, the present invention relates to an electron lithography apparatus using secondary electrons in which primary electrons are emitted using a cold emission technology for applying a voltage and emitting an electron at room temperature, the primary electrons are injected into an emitter, and secondary electrons are emitted at an exposed area from a patterned blocking mask formed on a surface of the emitter and projected onto a substrate.
2. Description of the Related Art
An electron projection lithography apparatus performs an exposure process by emitting electrons from an emitter and projecting the electrons onto an electron resist spaced apart from the emitter by a predetermined gap. The prior art discloses an electron projection lithography apparatus in which electrons are emitted by heating a pyroelectric emitter in a high vacuum state.
As a method of emitting electrons, a method of emitting secondary electrons by irradiating an emitter using an electron gun is known. When a rear side of a diamond substrate (an emitter) spaced apart from the electron gun by a predetermined gap in a vacuum chamber is irradiated using the electron gun, secondary electrons are emitted from a front side of the diamond substrate. In this case, a patterned mask is disposed on the front side of the diamond substrate, and an electron resist is placed at a predetermined distance from the front side of the diamond substrate. As such, the electron resist is patterned according to the mask pattern by the secondary electrons.
However, an electron gun is separately installed in a conventional electron projection lithography apparatus having the above structure, and thus, the lithography apparatus is inconveniently large. Also, the conventional electron projection lithography apparatus does not include a unit for forming a magnetic field, and thus, a resolving power is lowered when a pattern is projected onto a substrate with a scale of 1:1.
The present invention provides an electron projection lithography apparatus using secondary electrons having a compact structure in which primary electrons emitted by a field effect are incident on an emitter, and the secondary electrons are emitted from the emitter.
According to a feature of an embodiment of the present invention, there is provided an electron projection lithography apparatus using secondary electrons, the apparatus including a secondary electron emitter which is spaced apart from a substrate holder by a first predetermined interval and has a patterned mask formed on a surface thereof to face the substrate holder, a primary electron emitter which is spaced apart by a second predetermined interval from the secondary electron emitter in a direction opposite to the substrate holder and emits primary electrons to the secondary electron emitter, a second power supply which applies a second predetermined voltage between the substrate holder and the secondary electron emitter, a first power supply which applies a first predetermined voltage between the secondary electron emitter and the primary electron emitter, and a magnetic field generator which controls paths of secondary electrons emitted from the secondary electron emitter.
Preferably, the primary electron emitter is a plurality of micro-tips or carbon nanotubes to which the first predetermined voltage is applied from the first power supply and which emit the primary electrons toward the secondary electron emitter.
Preferably, a spacer is disposed between the primary electron emitter and the secondary electron emitter to maintain an interval therebetween.
The magnetic field generator may include permanent magnets or an electric magnet disposed below the first electron emitter and above the substrate holder. Alternatively, the magnetic field generator may be a DC magnetic field generator which surrounds sides of the secondary electron emitter and the substrate holder.
Meanwhile, preferably, the secondary electron emitter is a plate selected from the group consisting of a doped diamond single crystalline plate, a doped magnesium oxide plate, a doped AIN plate, and a doped AlGaN plate.
Preferably, the mask is formed of a material used to intercept electrons.
Preferably, a positive voltage is applied by the second power supply, a negative voltage is applied by the first power supply, and the secondary electron emitter is commonly grounded.